Eszopiclone

Mechanism of action:
Eszopiclone is the S-enantiomer of zopiclone. Eszopiclone binds to the benzodiazepine-binding site on the GABA_A receptor, with relatively higher affinity for receptors containing the α1 subunit. It acts as a positive allosteric modulator, enhancing the inhibitory effect of GABA and increasing the frequency of chloride channel (Cl⁻ channel) opening. This promotes chloride ion influx into neurons, causes hyperpolarization of the neuronal membrane potential, and reduces central nervous system excitability.
Reference(s):
1. Greenblatt DJ et al. (2012). Pharmacokinetic evaluation of eszopiclone: clinical and therapeutic implications. Expert Opin Drug Metab Toxicol.
2. Carlson JN et al. (2001). Sedative and anxiolytic effects of zopiclone's enantiomers and metabolite. Eur J Pharmacol.
